Generating material strength standards of aluminum alloys for research reactors II. Design fatigue curve under non-effective creep condition

Aluminum alloys are frequently used as structural materials for research reactors. The material strength standards, however, such as the yield strength values (Sy), the tensile strength values (Su) and the design fatigue curve—which are needed to use aluminum alloys as structural materials in “design by analysis”—for these materials have not been determined yet. Hence, a series of material tests was performed and the results were statistically analyzed with the aim of generating such material strength standards. This paper is the second in a series on the material standards of aluminum alloys, and describes the procedures used to generate the design fatigue curve. Creep effects on the design fatigue curve were evaluated, and a negligible creep region was determined by restrictions of the temperature and stress. The mean stress effect was evaluated using a modified Goodman line. The design fatigue curve presented has already been adopted in the Science and Technology Agency regulatory guide (standards for structural design of nuclear research plants).